1. Field of Invention
The present invention relates to a screw type liquid ring pump including a pump housing with an inlet and an outlet and a rotating helical screw rotor inside the housing, the rotor being connected with a shaft and a driving unit in the form of a motor, preferably an electric motor, whereby the pump housing represents an elongation of the motor housing forms an integrated or one-piece unit therewith.
2. Description of Related Art
Liquid ring pumps of the above kind are commonly known where the pump and the driving unit, usually an electric motor, are built together forming a unit. With such a solution, the production is simplified and the costs are reduced, mainly due to the fact that fewer constructional parts are required, such as only one shaft and two shaft bearings, compared to a conventional solution where the pump and rotor are manufactured as two independent units, each with two bearings. The structural length of the pump is much shorter with the one piece solution, whereby the pump requires less space and is more effective relative to the size of the pump.
In commonly-owned European patent No. 0 454 794, an example is shown of a conventional liquid ring type helical screw pump with a motor, each with its own shaft and own bearings, as well as an integrated solution where a common shaft is used for the pump and motor. With this last mentioned pump solution with a common shaft, the shaft seal between the pump and motor is provided, in relation to the motor housing, in front of the housing. A disadvantage with this solution is that leakage in the shaft seal will result in moisture entering into the bearing and further into the motor housing which, in the worst case, will result in break down of the motor. Another disadvantage is that the seal arrangement as such and the connection between the pump and the motor is relatively complicated and causes additional work in connection with the mounting and maintenance of the pump.